The present invention relates to a method and apparatus for the volume reduction and disposal of material, the primary application involving irradiated radioactive material. In particular, the present invention relates to method and apparatus for the removal, processing and disposal of pressure tubes and calandria tubes from CANDU(copyright) nuclear reactors.
In order to extend the operating life of CANDU(copyright) nuclear reactors, it may be necessary to undertake large scale fuel channel replacement. One of the key processes of large scale fuel channel replacement is the removal of the highly radioactive pressure tubes and calandria tubes from the reactor core.
The conventional process involves the removal of the approximately 6 meter long pressure tubes and calandria tubes whole, or cut in half at their midpoint. The reactor vault, on the side that the tubes are removed to, must be evacuated of personnel, which prevents parallel activities from occurring and thereby prolonging the work schedule. A very large and heavy lead-filled flask is used to transport the pressure tubes out of the reactor vault to disposal. It is a difficult and time consuming task to move this size of flask through the containment structure of a CANDUO(copyright) type nuclear reactor, requiring cranes or other heavy material handling equipment and personnel evacuation from the work area. This interrupts material, equipment and personnel movement for the whole reactor outage and is a major detriment in scheduling and critical path considerations. Thus, it is desirable to make the method of pressure tube and calandria tube removal and disposal more economically attractive.
The present invention provides a method and apparatus for reducing the volume of a cylindrical tube for disposal by the process of crushing flat and then shearing into small coupons. Shearing is preferably accomplished on a checkerboard grid of multiple intersecting planes and the resulting coupons are preferably substantially square in shape.
In accordance with the present invention there is provided an apparatus for reducing the disposal volume of an elongated cylindrical tube comprising a pair of inwardly opposed die blocks, means for moving said die blocks between an open position and a closed position, and feeder means for positioning an end portion of said cylindrical tube between said die blocks in said open position, each of said die blocks comprising an array of raised cutters and recessed pockets, each of said cutters of one of said die blocks adapted to be closely received into an opposed pocket of the other of said die blocks when said die blocks are moved from said open position to said closed position to sequentially crush said end portion to a substantially flat configuration and sever it into a plurality of coupons.
In accordance with another aspect of the invention, there is provided an apparatus for reducing the disposal volume of irradiated radioactive nuclear reactor cylindrical tubes comprising a movable mounting base adapted to be operatively positioned adjacent a reactor face at selected tube positions; a feeder unit mounted on said base for engaging and advancing said selected tube out of said reactor; a press assembly mounted on said base comprising a pair of inwardly opposed die blocks and means for moving said die blocks between an open position and a closed position, said die blocks being positioned to receive therebetween in said open position the end portion of said selected tube, each of said die blocks comprising an array of raised cutters and recessed pockets, each of said cutters of one of said die blocks adapted to be closely received into an opposed pocket of the other of said die blocks, whereby when said die blocks are moved from said open position to said closed position, said end portion is sequentially crushed to a substantially flat configuration and severed into a plurality of coupons.
In accordance with another aspect of the invention, there is provided a method for reducing the disposal volume of an elongated cylindrical tube comprising: (a) positioning the end portion of said cylindrical tube between a pair of inwardly opposed die blocks movable between an open position and a closed position, each of said die blocks comprising an array of raised cutters and recessed pockets, each of said cutters of one of said die blocks adapted to be closely received into an opposed pocket of the other of said die blocks when said die blocks are moved from said open position to said closed position; (b) moving said die blocks from said open position to said closed position to sequentially crush said end portion to a substantially flat configuration and sever it into a plurality of coupons; and (c) repeating steps (a) and (b) until said cylindrical tube is severed into coupons.
In accordance with another aspect of the invention, there is provided a method for reducing the disposal volume of irradiated radioactive nuclear reactor cylindrical tubes comprising: (a) engaging the end of a selected tube at the reactor face and advancing a portion of said selected tube out of said reactor; (b) positioning the end portion of said cylindrical tube between a pair of inwardly opposed die blocks movable between an open position and a closed position, each of said die blocks comprising an array of raised cutters and recessed pockets, each of said cutters of one of said die blocks adapted to be closely received into an opposed pocket of the other of said die blocks when said die blocks are moved from said open position to said closed position; (c) moving said die blocks from said open position to said closed position to sequentially crush said end portion to a substantially flat configuration and sever it into a plurality of coupons; and (d), repeating steps (b) and (c) until said cylindrical tube is severed into coupons.
The construction and method of operation of the invention will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.